refactor: Major reorganization of optimization_engine module structure

BREAKING CHANGE: Module paths have been reorganized for better maintainability.
Backwards compatibility aliases with deprecation warnings are provided.

New Structure:
- core/           - Optimization runners (runner, intelligent_optimizer, etc.)
- processors/     - Data processing
  - surrogates/   - Neural network surrogates
- nx/             - NX/Nastran integration (solver, updater, session_manager)
- study/          - Study management (creator, wizard, state, reset)
- reporting/      - Reports and analysis (visualizer, report_generator)
- config/         - Configuration management (manager, builder)
- utils/          - Utilities (logger, auto_doc, etc.)
- future/         - Research/experimental code

Migration:
- ~200 import changes across 125 files
- All __init__.py files use lazy loading to avoid circular imports
- Backwards compatibility layer supports old import paths with warnings
- All existing functionality preserved

To migrate existing code:
  OLD: from optimization_engine.nx_solver import NXSolver
  NEW: from optimization_engine.nx.solver import NXSolver

  OLD: from optimization_engine.runner import OptimizationRunner
  NEW: from optimization_engine.core.runner import OptimizationRunner

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

optimization_engine/processors/surrogates/__init__.py

@@ -0,0 +1,79 @@
+"""
+Surrogate Models
+================
+
+Neural network and ML surrogate models for FEA acceleration.
+
+Available modules:
+- neural_surrogate: AtomizerField neural network surrogate
+- generic_surrogate: Flexible surrogate interface
+- adaptive_surrogate: Self-improving surrogate
+- simple_mlp_surrogate: Simple multi-layer perceptron
+- active_learning_surrogate: Active learning surrogate
+- surrogate_tuner: Hyperparameter tuning
+- auto_trainer: Automatic model training
+- training_data_exporter: Export training data from studies
+
+Note: Imports are done on-demand to avoid import errors from optional dependencies.
+"""
+
+# Lazy imports to avoid circular dependencies and optional dependency issues
+def __getattr__(name):
+    """Lazy import mechanism for surrogate modules."""
+    if name == 'NeuralSurrogate':
+        from .neural_surrogate import NeuralSurrogate
+        return NeuralSurrogate
+    elif name == 'create_surrogate_for_study':
+        from .neural_surrogate import create_surrogate_for_study
+        return create_surrogate_for_study
+    elif name == 'GenericSurrogate':
+        from .generic_surrogate import GenericSurrogate
+        return GenericSurrogate
+    elif name == 'ConfigDrivenSurrogate':
+        from .generic_surrogate import ConfigDrivenSurrogate
+        return ConfigDrivenSurrogate
+    elif name == 'create_surrogate':
+        from .generic_surrogate import create_surrogate
+        return create_surrogate
+    elif name == 'AdaptiveSurrogate':
+        from .adaptive_surrogate import AdaptiveSurrogate
+        return AdaptiveSurrogate
+    elif name == 'SimpleSurrogate':
+        from .simple_mlp_surrogate import SimpleSurrogate
+        return SimpleSurrogate
+    elif name == 'ActiveLearningSurrogate':
+        from .active_learning_surrogate import ActiveLearningSurrogate
+        return ActiveLearningSurrogate
+    elif name == 'SurrogateHyperparameterTuner':
+        from .surrogate_tuner import SurrogateHyperparameterTuner
+        return SurrogateHyperparameterTuner
+    elif name == 'tune_surrogate_for_study':
+        from .surrogate_tuner import tune_surrogate_for_study
+        return tune_surrogate_for_study
+    elif name == 'AutoTrainer':
+        from .auto_trainer import AutoTrainer
+        return AutoTrainer
+    elif name == 'TrainingDataExporter':
+        from .training_data_exporter import TrainingDataExporter
+        return TrainingDataExporter
+    elif name == 'create_exporter_from_config':
+        from .training_data_exporter import create_exporter_from_config
+        return create_exporter_from_config
+
+    raise AttributeError(f"module 'optimization_engine.processors.surrogates' has no attribute '{name}'")
+
+__all__ = [
+    'NeuralSurrogate',
+    'create_surrogate_for_study',
+    'GenericSurrogate',
+    'ConfigDrivenSurrogate',
+    'create_surrogate',
+    'AdaptiveSurrogate',
+    'SimpleSurrogate',
+    'ActiveLearningSurrogate',
+    'SurrogateHyperparameterTuner',
+    'tune_surrogate_for_study',
+    'AutoTrainer',
+    'TrainingDataExporter',
+    'create_exporter_from_config',
+]